The present invention generally relates to forming field effect transistors and more specifically to the creation of shallower and sharper junctions, while maximizing dopant activation in processes that increase the oxygen content of the top surface of a silicon substrate before epitaxially growing a silicon layer on the silicon substrate, where the increased oxygen content substantially limits dopants within the epitaxial silicon layer from moving into the silicon substrate.
As devices are scaled to smaller and smaller dimensions, shallower and sharper junctions are needed in transistors to control short channel effects and series resistance. The ability to reduce the oxide thickness (scale the oxide) is becoming more difficult in field effect transistor (FETs) and other similar integrated circuit design technologies. As it becomes more difficult to scale the oxide, it becomes more important to reduce the junction depth and increase junction sharpness. However, it is becoming more difficult to obtain shallower and sharper junctions with ion implantation and rapid thermal annealing as the devices become smaller. Therefore, there is a need for new methodologies and structures that create shallower and sharper junctions while maximizing dopant activation in processes that are consistent with current manufacturing techniques.